Fire fighting often requires laying down and connecting long lengths of heavy hose capable of withstanding high pressure. Hose today is typically connected by means of quick, twist-type connectors. Many commercially available couplings require only turning a mated pair of coupling faces together to achieve a watertight joint. The coupling faces rotate about each hose end so that hose need not be turned to get proper alignment. The coupling face fittings are rotated to get proper alignment of locking lugs of the two coupling faces to be joined. The hoses are then pulled into abutting relationship and one coupling face is rotated relative to the other until the connecting lugs engage, forming a tight joint between the hose sections.
For many couplings, only a quarter or one-third turn of a coupling face is required to achieve a watertight connection. The coupling faces are often provided with protruding lugs for receiving a wrench end to tighten up the fitting. These lugs may be arranged so that when a seal is achieved, the lugs across the two coupling faces line up longitudinally with respect to hose direction. This feature is especially valuable for ensuring that the joint is fully engaged, particularly in view of the often difficult, low-visibility conditions under which fire fighters work.
While the present day quick-connect, twist-to-seal couplings save a great deal of time and effort, a safety problem has developed. As fire hose is removed from a fire truck, random direction kinks or twists in the hose are often created. It is generally impossible to prevent these kinks in laying the hose, particularly when long lengths of up to 600 feet of 5-inch line are not unusual. The end of a hose run from the fire location is connected to a stationary object, such as a pumper truck, heavy distribution manifold, or fire hydrant. The twists in the hose become a problem when the fire hose is pressurized. As air is displaced through the filling hose, the kinks cause the hose to turn in the direction of the kinks. The turning or twisting motion is imparted to the hose with such force that the hand- or wrench-tightened twist couplings may twist loose. The problem is particularly acute where the hose is fastened to a stationary object whose one coupling face is substantially fixed with respect to the other coupling face. The twisting motion imparted by the hose kinks and filling action can rotate the relatively less fixed coupling face, causing it to separate from the fixed coupling face. The rotating line blows off the stationary object or turns over a large manifold with great force, causing damage to fire fighters, bystanders, and property. Once the fittings are pressurized with water, the danger is over since the pressure in the line holds the fitting connecting mechanism tightly in place. At the initiation of pressurization, however, there are no such forces holding the connecting mechanism together and the coupling is easily defeated by the forces generated in bringing line pressure up to working pressure in combination with the random direction kinks.
The necessity of locking quick-connect, nonthreaded hose couplings together has been recognized to some degree in the prior art, as discussed below. However, prior art locking devices, most lightly because they did not have to deal with the larger diameter fire hose of today and the weights and pressures connected therewith, are insufficient to resist the uncoupling danger.
In addition, modern fire fighters have gone to great lengths to make sure hose coupling systems are independent of end-to-end orientation, or "unisex" in nature. That is, any hose length must be able to be connected to any other similar diameter hose or pumper truck or similar fixed connection. Many times during fighting fires, hose routings and connections must be changed. There is no time to turn hose lengths around to ensure proper coupling.
Present day coupling systems are also designed for speed, with connecting mechanisms that do not require turning hose lengths for special coupling alignments. As noted above, coupling faces rotate for alignment while the hose remains stationary.
Another factor in today's coupling systems is that they must be designed for ease and simplicity of operation. Fire fighters wear heavy protection clothing, and in general, find it difficult to operate couplings or couplings locks that require a great deal of digital dexterity.
The prior art locking mechanims are designed and adapted for couplings of the type requiring special end-to-end orientation. Most require special alignment in order to establish a connection. Many are complex and difficult to operate. A number of typical prior art locking mechanisms are described in the following paragraphs.
Lehotzky, in U.S. Pat. No. 726,077, discloses a quick-disconnect fire hose coupling utilizing a latch and turn-key combination to restrict relative longitudinal displacement of the couplings. The Lehotzky patent does not provide a positive means of preventing relative rotational displacement of the coupling faces, which is absolutely necessary in the face of modern high-pressure fire-fighting pumps. In addition, the Lehotzky latch is limited and integral to the Lehotzky hose coupling and is not adaptable to twist-type, high-pressure, quick-connect couplings currently being utilized in the field.
Berg, in U.S. Pat. No. 1,080,675, discloses a threadless hose coupling incorporating an internal locking ring rotated by an external handle which is stowed in grooves provided in the female end of the the coupling. The Berg patent has a plurality of moving parts and is not adaptable to modern fire-fighting, high-pressure, quick-connect hose fittings.
Strausser, in U.S. Pat. No. 1,200,266, discloses a threadless hose coupling which relies on primary and auxiliary locking dogs as the sole means of coupling two hoses. Thus the locking means is extremely heavy and has a plurality of moving parts, both internally and externally. The Strausser invention requires specially designed hose ends, incorporating its coupling, which are not used in modern fire-fighting systems. There is also no provision in the Strausser patent to restrict relative rotation between the sides of the coupling other than by pure force and friction, which generate fatigue failures of the system.
Hansen, in U.S. Pat. No. 1,858,992, discloses a hose coupling equipped with spring-actuated yokes. The Hansen invention is not adaptable to existing quarter-turn, high-pressure, quick-connect fire hose couplings and relies on spring tension to maintain its yokes in place.
Heath, in U.S. Pat. No. 3,807,774, discloses a locking device to prevent a tube fitting from rotating, comprising an external face on the female side of the fitting equipped with continuous serrations around its circumference and a wire threaded through a hole in an external nut on the face of the male side of the fitting perpendicular to the longitudinal axis of the fitting so as to engage the serrations when the wire is rotated within the hole in the external nut. The Heath device is too flimsy and requires a special coupling design. Both of these deficiencies make it impractical for quater-turn, high-pressure, quick-connect fire hose couplings.